/**
* And now for a little assembly. Put together the buttons, progress bar and status text field.
*/
Example1(String name) {
setBorder(BorderFactory.createTitledBorder(BorderFactory.createLineBorder(Color.black), name));
progressBar.setMaximum(NUMLOOPS);
startButton = new JButton("Start");
startButton.addActionListener(startListener);
startButton.setEnabled(true);
interruptButton = new JButton("Cancel");
interruptButton.addActionListener(interruptListener);
interruptButton.setEnabled(false);
JComponent buttonBox = new JPanel();
buttonBox.add(startButton);
buttonBox.add(interruptButton);
setLayout(new BoxLayout(this, BoxLayout.Y_AXIS));
add(buttonBox);
add(progressBar);
add(statusField);
statusField.setAlignmentX(CENTER_ALIGNMENT);
buttonBox.setBorder(spaceBelow);
Border pbBorder = progressBar.getBorder();
progressBar.setBorder(BorderFactory.createCompoundBorder(spaceBelow, pbBorder));
}
class Example1 extends JPanel {
JProgressBar progressBar = new JProgressBar();
static int NUMLOOPS = 100;
JLabel statusField = new JLabel("Click Start to begin", JLabel.CENTER);
SwingWorker worker;
JButton startButton;
JButton interruptButton;
Border spaceBelow = BorderFactory.createEmptyBorder(0, 0, 5, 0);
JButton getStartButton() {
return startButton;
}
/**
* When the worker needs to update the GUI we do so by queuing a Runnable for the event
* dispatching thread with SwingUtilities.invokeLater(). In this case we're just changing the
* progress bars value.
*/
void updateStatus(final int i) {
Runnable doSetProgressBarValue =
new Runnable() {
public void run() {
progressBar.setValue(i);
}
};
SwingUtilities.invokeLater(doSetProgressBarValue);
}
/**
* This method represents the application code that we'd like to run on a separate thread. It
* simulates slowly computing a value, in this case just a string 'All Done'. It updates the
* progress bar every half second to remind the user that we're still busy.
*/
Object doWork() {
try {
for (int i = 0; i < NUMLOOPS; i++) {
updateStatus(i);
if (Thread.interrupted()) {
throw new InterruptedException();
}
Thread.sleep(500);
}
} catch (InterruptedException e) {
updateStatus(0);
return "Interrupted"; // SwingWorker.get() returns this
}
return "All Done"; // or this
}
/**
* This action listener, called by the "Start" button, effectively forks the thread that does the
* work.
*/
ActionListener startListener =
new ActionListener() {
public void actionPerformed(ActionEvent event) {
startButton.setEnabled(false);
interruptButton.setEnabled(true);
statusField.setText("Working...");
/* Constructing the SwingWorker() causes a new Thread
* to be created that will call construct(), and then
* finished(). Note that finished() is called even if
* the worker is interrupted because we catch the
* InterruptedException in doWork().
*/
worker =
new SwingWorker() {
public Object construct() {
return doWork();
}
public void finished() {
startButton.setEnabled(true);
interruptButton.setEnabled(false);
statusField.setText(get().toString());
}
};
}
};
/**
* This action listener, called by the "Cancel" button, interrupts the worker thread which is
* running this.doWork(). Note that the doWork() method handles InterruptedExceptions cleanly.
*/
ActionListener interruptListener =
new ActionListener() {
public void actionPerformed(ActionEvent event) {
interruptButton.setEnabled(false);
worker.interrupt();
startButton.setEnabled(true);
}
};
/**
* And now for a little assembly. Put together the buttons, progress bar and status text field.
*/
Example1(String name) {
setBorder(BorderFactory.createTitledBorder(BorderFactory.createLineBorder(Color.black), name));
progressBar.setMaximum(NUMLOOPS);
startButton = new JButton("Start");
startButton.addActionListener(startListener);
startButton.setEnabled(true);
interruptButton = new JButton("Cancel");
interruptButton.addActionListener(interruptListener);
interruptButton.setEnabled(false);
JComponent buttonBox = new JPanel();
buttonBox.add(startButton);
buttonBox.add(interruptButton);
setLayout(new BoxLayout(this, BoxLayout.Y_AXIS));
add(buttonBox);
add(progressBar);
add(statusField);
statusField.setAlignmentX(CENTER_ALIGNMENT);
buttonBox.setBorder(spaceBelow);
Border pbBorder = progressBar.getBorder();
progressBar.setBorder(BorderFactory.createCompoundBorder(spaceBelow, pbBorder));
}
Example1() {
this("Example 1");
}
}
